Substrate with multi-layer resin structure and semiconductor device including the substrate

ABSTRACT

A substrate for semiconductor elements includes a terminal part including a first surface, a second surface opposite to the first surface, and side surfaces joining the first surface and the second surface, and a resin part covering the side surfaces and exposing the first surface of the terminal part. The resin part has a multi-layer structure including a first resin and a second resin, and the first resin is provided in contact with the side surfaces of the terminal part. The first resin and the second resin include a filler, and an amount of the filler included in the first resin is smaller than an amount of the filler included in the second resin.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2017-180608, filed on Sep. 20,2017, the entire contents of which are incorporated herein by reference.

FIELD

Certain aspects of the embodiments discussed herein are related to asubstrate for semiconductor elements, a method of manufacturing thesubstrate for semiconductor elements, a semiconductor device, and amethod of manufacturing the semiconductor device.

BACKGROUND

An example of a known substrate for semiconductor elements is mountedwith the semiconductor elements to form a part of a semiconductordevice. The substrate for semiconductor elements is manufactured byforming a groove structure that becomes a wiring pattern on one surfaceof a metal plate. After filling the groove structure with a liquidpremold resin, the liquid premold resin is cured by heating.

However, in the substrate for semiconductor elements having thestructure described above, adhesion between the premold resin and themetal plate is poor. In addition, the substrate for semiconductorelements may warp due to differences between coefficients of thermalexpansion of the premold resin and the metal plate.

An example of the substrate for semiconductor elements is proposed inJapanese Patent No. 5526575 (or Japanese Laid-Open Patent PublicationNo. 2010-238694, for example.

SUMMARY

Accordingly, it is an object in one aspect of the embodiments to providea substrate for semiconductor elements, a method of manufacturing thesubstrate for semiconductor elements, a semiconductor device, and amethod of manufacturing the semiconductor device, that can improve theadhesion between a resin and a metal in the substrate for semiconductorelements, and to reduce warping of the substrate for semiconductorelements.

According to one aspect of the embodiments, a substrate forsemiconductor elements includes a terminal part including a firstsurface, a second surface opposite to the first surface, and sidesurfaces joining the first surface and the second surface; and a resinpart covering the side surfaces and exposing the first surface of theterminal part, wherein the resin part has a multi-layer structureincluding a first resin and a second resin, wherein the first resin isprovided in contact with the side surfaces of the terminal part, whereinthe first resin and the second resin include a filler, and wherein anamount of the filler included in the first resin is smaller than anamount of the filler included in the second resin.

According to another aspect of the embodiments, a semiconductor deviceincludes the substrate for semiconductor elements described above; and asemiconductor element mounted on a surface of the substrate forsemiconductor elements, wherein the semiconductor element and theterminal part are electrically connected.

The object and advantages of the embodiments will be realized andattained by means of the elements and combinations particularly pointedout in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and notrestrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view illustrating an example of a substrate forsemiconductor elements in a first embodiment;

FIG. 2A, FIG. 2B, and FIG. 2C are diagrams illustrating an example of aunit substrate forming the substrate for semiconductor elements in thefirst embodiment;

FIG. 3 is a bottom view illustrating an example of the unit substrateforming the substrate for semiconductor elements in the firstembodiment;

FIG. 4A, FIG. 4B, FIG. 4C, FIG. 4D, and FIG. 4E are diagramsillustrating examples of manufacturing processes of the substrate forsemiconductor elements in the first embodiment;

FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5D are diagrams illustratingexamples of the manufacturing processes of the substrate forsemiconductor elements in the first embodiment;

FIG. 6A, FIG. 6B, and FIG. 6C are diagrams illustrating examples of themanufacturing processes of the substrate for semiconductor elements inthe first embodiment;

FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7D are diagrams illustratingexamples of manufacturing processes of a semiconductor device in thefirst embodiment;

FIG. 8A, FIG. 8B, and FIG. 8C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements in afirst modification of the first embodiment;

FIG. 9A and FIG. 9B are diagrams illustrating examples of manufacturingprocesses of the substrate for semiconductor elements in the firstmodification of the first embodiment;

FIG. 10A, FIG. 10B, and FIG. 10C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the firstmodification of the first embodiment;

FIG. 11A, FIG. 11B, and FIG. 11C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements in asecond modification of the first embodiment;

FIG. 12A, FIG. 12B, and FIG. 12C are diagrams illustrating examples ofmanufacturing processes of the substrate for semiconductor elements inthe second modification of the first embodiment;

FIG. 13A, FIG. 13B, and FIG. 13C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the secondmodification of the first embodiment;

FIG. 14 is a diagram illustrating an example of the manufacturingprocess of the substrate for semiconductor elements in the secondmodification of the first embodiment;

FIG. 15A, FIG. 15B, and FIG. 15C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements in athird modification of the first embodiment;

FIG. 16A, FIG. 16B, and FIG. 16C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the thirdmodification of the first embodiment;

FIG. 17A, FIG. 17B, and FIG. 17C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements in afourth modification of the first embodiment;

FIG. 18 is a diagram illustrating an example of a manufacturing processof the substrate for semiconductor elements in the fourth modificationof the first embodiment;

FIG. 19A, FIG. 19B, and FIG. 19C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements in afifth modification of the first embodiment;

FIG. 20A, FIG. 20B, FIG. 20C, and FIG. 20D are diagrams illustratingexamples of manufacturing processes of the substrate for semiconductorelements in the fifth modification of the first embodiment;

FIG. 21A and FIG. 21B are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the fifthmodification of the first embodiment;

FIG. 22A, FIG. 22B, and FIG. 22C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements in asixth modification of the first embodiment; and

FIG. 23A, FIG. 23B, and FIG. 23C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the sixthmodification of the first embodiment.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention will be described withreference to the accompanying drawings. In the drawings, those partsthat are the same are designated by the same reference numerals, and arepeated description of the same parts may be omitted.

First Embodiment

[Structure of Substrate for Semiconductor Elements]

FIG. 1 is a plan view illustrating an example of a substrate forsemiconductor elements in a first embodiment. As illustrated in FIG. 1,a substrate 1 for semiconductor elements has a structure in which aplurality of unit substrate groups 20, indicated by one-dot chain lines,are separated from each other and arranged on a substrate frame 10having an approximately rectangular shape in the plan view.

In the example illustrated in FIG. 1, three unit substrate groups 20 arearranged in one column. However, the number of unit substrate groups 20that are arranged may be determined arbitrarily. In addition, the unitsubstrate groups 20 may be arranged in a plurality of columns. Further,although a slit 10 x is provided between two mutually adjacent unitsubstrate groups 20 in the example illustrated in FIG. 1, the slit 10 xmay be omitted.

The substrate 1 for semiconductor elements may be made of a materialselected from copper (Cu), Cu-based alloys, iron-nickel (Fe—Ni),Fe—Ni-based alloys, stainless steel, or the like, for example.

A plurality of unit substrates 30 are arranged in a matrix arrangementin each unit substrate group 20. The unit substrates 30 are finallymounted with semiconductor elements, and are cut at cutting positions Cindicated by dotted lines, to form a part of individual semiconductordevices, respectively. In the example illustrated in FIG. 1, the unitsubstrate group 20 is formed by six rows by six columns of unitsubstrates 30 arranged in the matrix arrangement. However, the number ofunit substrates 30 forming the unit substrate group 20 may be determinedarbitrarily.

FIG. 2A through FIG. 2C are diagrams illustrating an example of the unitsubstrate forming the substrate for semiconductor elements in the firstembodiment. FIG. 2A illustrates a plan view, FIG. 2B illustrates a crosssection along a line A-A in FIG. 2A, and FIG. 2C illustrates a crosssection along a line B-B in FIG. 2A. FIG. 3 is a bottom viewillustrating an example of the unit substrate forming the substrate forsemiconductor elements in the first embodiment.

As illustrated in FIGS. 2A through 2C and FIG. 3, the unit substrate 30includes a die pad 31, leads 32, a resin part 33, metal layers 34 and35, a frame part 38, and support bars 39.

In this embodiment, for the sake of convenience, a surface of the unitsubstrate 30 on which the metal layers 34 and 35 are formed, is referredto as an upper surface or a first surface of the unit substrate 30, andan opposite surface of the unit substrate 30 on which the metal layers34 and 35 are not formed, is referred to as a lower surface or a secondsurface of the unit substrate 30 opposite to the upper surface or thefirst surface of the unit substrate 30. However, the unit substrate 30may be arranged upside down, or may be arranged at an arbitrary angle.In addition, a plan view of an object refers to a view from a normaldirection of an upper surface 31 a of the die pad 31, and a planar shapeof the object refers to a shape in the view from the normal direction ofthe upper surface 31 a of the die pad 31.

The die pad 31 is an example of a semiconductor element mounting parthaving an upper surface 31 a on which a semiconductor element ismounted, and a lower surface 31 b opposite to the upper surface 31 a.For example, the die pad 31 is formed approximately at a central part ofthe unit substrate 30, and has a planar shape that is a rectangularshape. The frame part 38 is provided between adjacent unit substrates30. In the plan view, four corners on an inner side of the frame part 38and four corners on an outer side of the die pad 31 are connected byfour elongated support bars 39 that are arranged obliquely ordiagonally. The upper surface 31 a of the die pad 31, upper surfaces 32a of the leads 32, an upper surface of the frame part 38, and uppersurfaces of the support bars 39 may be arranged on the same plane, forexample.

A cutout part 311 is provided in an annular shape, for example, in thelower surface 31 b at the outer peripheral part of the die pad 31. Athickness T₁ of the die pad 31 at a part (that is, a part that is notthinned) where the cutout part 311 is not provided may be approximately75 μm to approximately 200 μm, for example. A thickness T₂ of the diepad 31 at a part (that is, a part that is thinned) where the cutout part311 is provided may be approximately one-half the thickness T₁, forexample. Lower surfaces of the frame part 38 and the support bars 39 arehalf-etched, and thicknesses of the frame part 38 and the support bars39 are approximately the same as the thickness T₂ of the die pad 31 atthe part where the cutout part 311 is provided.

In the plan view, the plurality of leads 32 having the elongated shapeare provided to extend from a predetermined region on an inner side ofthe frame part 38 toward the die pad 31. Each lead 32 is separated fromthe frame part 38 when the unit substrate 30 is cut at cutting positionsC (or cut along cuttable positions C) during a manufacturing process ofthe semiconductor device, as will be described later. The leads 32becomes electrically insulated from each other after being separatedfrom the frame part 38.

The leads 32 form terminal parts that are arranged at positionsseparated from the outer peripheral part of the die pad 31. The leads 32are separated from each other, and are arranged on the outer side of thedie pad 31. A cutout part 321 is provided in the lower surface 32 b atan end part of the lead 32 facing the outer peripheral part of the diepad 31. A thickness T₃ of the lead 32 at a part (that is, a part that isnot thinned) where the cutout part 321 is not provided may beapproximately 75 μm to approximately 200 μm, for example. A thickness T₄of the lead 32 at a part (that is, a part that is thinned) where thecutout part 321 is provided may be approximately one-half the thicknessT₃, for example. The thickness T₁ and the thickness T₃ are approximatelythe same, and the thickness T₂ and the thickness T₄ are approximatelythe same.

The resin part 33 hold the die pad 31 and the leads 32 in a state inwhich the upper surface 31 a of the die pad 31 and the upper surfaces 32a of the leads 32 are exposed. The resin part 33 is provided so as tofill the cutout part 311 and the cutout part 321.

More particularly, in the plan view, the resin part 33 is provided so asto fill regions where the die pad 31, the leads 32, the frame part 38,and the support bars 39 are not provided. In addition, the resin part 33is provided to fill the cutout parts 311 and 321, and to cover thehalf-etched lower surfaces of the frame part 38 and the support bars 39.In other words, the frame part 38 and the support bars 39 are providedon the resin part 33. Accordingly, in the bottom view of the unitsubstrate 30 illustrated in FIG. 3, inner wall surfaces of the cutoutparts 311 and 321 and the lower surfaces of the frame part 38 and thesupport bars 39 are not exposed from the resin part 33. The resin part33 exposes the lower surface 31 b of the die pad 31 and the lowersurfaces 32 b of the leads 32.

The resin part 33 has a multi-layer structure, or a laminated structure,including a first resin 331 and a second resin 332. The first resin 331is arranged to make contact with the inner wall surfaces of the cutoutpart 311 and the inner wall surfaces of the cutout part 321. The secondresin 332 is arranged to sandwich the first resin 331 between the secondresin 332 and each of the inner wall surfaces of the cutout part 311 andthe inner wall surfaces of the cutout part 321. In other words, thefirst resin 331 exists between the second resin 332 and each of theinner wall surfaces of the cutout part 311 and the inner wall surfacesof the cutout part 321. The second resin 332 does not make contact withthe inner wall surfaces of the cutout part 311, and also does not makecontact with the inner wall surfaces of the cutout part 321.

The first resin 331 extends from inside the cutout part 311 toward apart of a side surface (lower part of the side surface) of the die pad31, to directly cover the part of the side surface of the die pad 31. Inaddition, the first resin 331 extends from inside the cutout part 321toward a part of side surfaces (lower part of the side surfaces) of theleads 32, to directly cover the part of the side surfaces of the leads32. The second resin 332 is arranged to stretch over the first resin 331that extends from inside the cutout part 311 toward the part of the sidesurface (lower part of the side surface) of the die pad 31, to directlycover the part of the side surface of the die pad 31. In addition, thesecond resin 332 is arranged to stretch over the first resin 331 thatextends from inside the cutout part 321 toward the part of side surfaces(lower part of the side surfaces) of the leads 32, to directly cover thepart of the side surfaces of the leads 32.

The part of the side surface of the die pad 31, not provided with thecutout part 311 and closer to the upper surface 31 a, is exposed fromthe resin part 33. In addition, the part of the side surface of the lead32, not provided with the cutout part 321 and closer to the uppersurface 32 a, is exposed from the resin part 33.

The lead 32 includes a main lead body that extends along an uppersurface of the resin part 33 in an in-plane direction. An upper surfaceand side surfaces of the main lead body of the lead 32 are exposed fromthe resin part 33, and a lower surface of the main lead body makescontact with the resin part 33 (first resin 331). The upper surface 32 aof the lead 32 forms the upper surface of the main lead body.

The lead 32 includes an external connection part that projects downwardfrom the main lead body, and this external connection part is exposedfrom a lower surface of the resin part 33. Side surfaces of the externalconnection part make contact with the resin part 33 (first resin 331),and a lower surface of the external connection part is exposed from thelower surface of the resin part 33. The lower surface 32 b of the lead32 that is exposed from the resin part 33 forms the lower surface of theexternal connection part.

Accordingly, the resin part 33 fills the inside of the cutout part 311and the inside of the cutout part 321, and covers the lower parts of theside surfaces of the die pad 31 and the leads 32. In other words, theupper surfaces of the die pad 31 and the leads 32 project from the uppersurface of the resin part 33. In addition, the first resin 331 includesparts in contact with the die pad 31 and the leads 32. On the otherhand, the second resin 332 includes no parts in contact with the die pad31 and the leads 32.

The first resin 331 is arranged to make contact with the lower surfaceof the frame part 38 and the lower surfaces of the support bars 39. Thesecond resin 332 is arranged to sandwich the first resin between thesecond resin 332 and each of the lower surface of the frame part 38 andthe lower surfaces of the support bars 39. In other words, the firstresin 331 exists between the second resin 332 and each of the lowersurface of the frame part 38 and the lower surfaces of the support bars39. The second resin 332 does not make contact with the lower surface ofthe frame part 38, and also does not make contact with the lowersurfaces of the support bars 39.

The lower surface of the resin part 33 (lower surface of the first resin331 and lower surface of the second resin 332), the lower surface 31 bof the die pad 31, and the lower surfaces 32 b of the leads 32 may bearranged on the same plane, for example.

The first resin 331 and the second resin 332 may be made of a materialsuch as an epoxy resin, a polyimide resin, or the like. The first resin331 and the second resin 332 include a filler, such as silica, alumina,or the like, for example. An amount of the filler included in the firstresin 331 is smaller than an amount of the filler included in the secondresin 332. A type of the filler included in the first resin 331 may bethe same as, or may be different from, a type of the filler included inthe second resin 332.

By reducing the amount of the filler included in the first resin 331 incontact with the die pad 31, the leads 32, the frame part 38, and thesupport bars 39, it is possible to increase a contact area of a resinpart (part excluding the filler) forming the first resin 331 and the diepad 31, the leads 32, the frame part 38, and the support bars 39. Forthis reason, it is possible to improve an adhesion of the first resin331 with respect to the die pad 31, the leads 32, the frame part 38, andthe support bars 39.

On the other hand, by increasing the amount of the filler included inthe second resin 332, it is possible to easily adjust a coefficient ofthermal expansion of the resin part 33. For example, when the amount ofthe filler included in the second resin 332 is adjusted so that thecoefficient of thermal expansion of the resin part 33 becomesapproximately the same as coefficients of expansion of the die pad 31,the leads 32, the frame part 38, and the support bars 39, it is possibleto reduce warping of the substrate 1 for semiconductor elements.

The annular metal layer 34 is formed on the upper surface 31 a of thedie pad 31, in a region located at the outer peripheral part of the diepad 31. In addition, the lead 32 has a reduced width from approximatelythe central part toward the outer side of the die pad 31 along alongitudinal direction of the lead 32. The metal layer 35 is formed onthe upper surface 32 a of the lead 32 at an end part (end part facingthe outer peripheral part of the die pad 31) of a region of the uppersurface 32 a of the lead 32 having the reduced width. It is notessential that the lead 32 has the reduced width from approximately thecentral part toward the outer side of the die pad 31 along thelongitudinal direction of the lead 32, and the lead 32 may have aconstant width along the longitudinal direction thereof.

The metal layers 34 and 35 may be used as bonding pads for electricallyconnecting to electrodes of the semiconductor element mounted on the diepad 31 via metal wires. For example, the metal layers 34 and 35 may beformed by a Ag layer, a Au layer, a Sn layer, a Ni/Au layer structure(metal layer structure including a Ni layer and a Au layer that arestacked in this order), a Ni/Pd/Au layer structure (metal layerstructure including a Ni layer, a Pd layer, and a Au layer that arestacked in this order), or the like.

[Method of Manufacturing Substrate for Semiconductor Elements]

Next, a method of manufacturing the substrate for semiconductor elementsin the first embodiment, with reference to illustrations of the unitsubstrate 30.

FIG. 4A through FIG. 4E, FIG. 5A through FIG. 5D, and FIG. 6A throughFIG. 6C are diagrams illustrating examples of manufacturing processes ofthe substrate for semiconductor elements in the first embodiment. FIG.4A through FIG. 4E, FIG. 5A through FIG. 5D, and FIG. 6A through FIG. 6Cillustrate cross sections corresponding to the cross section illustratedin FIG. 2B.

First, in the process illustrated in FIG. 4A, a plate member (or metalplate) 10A made of a metal material, having the same shape as thesubstrate frame 10 illustrated in FIG. 1, is prepared. For example, themetal material forming the plate member 10A may be copper (Cu), Cu-basedalloys, iron-nickel (Fe—Ni), Fe—Ni-based alloys, stainless steel, or thelike. A thickness of the plate member 10A may be approximately 75 μm toapproximately 200 μm, for example.

Next, a photoresist 300 is formed on an entire upper surface of theplate member 10A, and a photoresist 310 is formed on an entire lowersurface of the plate member 10A. For example, the photoresist 300 andthe photoresist 310 may be made of a dry film resist or the like. Thephotoresist 310 is exposed, developed, and patterned so as to expose theregions that are to be half-etched. The photoresist 310 is patterned soas to expose the regions where the cutout parts 311 and 321 are to beprovided, and the regions where the frame part 38 and the support bars39 are to be provided. In this state, the photoresist 300 still coversthe entire upper surface of the plate member 10A.

Next, in the process illustrated in FIG. 4B, the plate member 10A ishalf-etched, using the photoresist 300 and the photoresist 310 asetching masks. The regions not covered by the resist 310 are half-etchedfrom the lower surface of the plate member 10A, to form a cavity part 10y that caves in from the lower surface of the plate member 10A towardthe upper surface of the plate member 10A. In a case in which the platemember 10A is made of copper, the cavity part 10 y may be formed by awet etching using a cupric chloride solution, for example. The cavitypart 10 y is formed in the regions where the cutout parts 311 and 321are to be provided, and in the regions where the frame part 38 and thesupport bars 39 are to be provided. In other words, in the processillustrated in FIG. 4B, the lower surface of the plate member 10A ishalf-etched in the regions where the frame part 38 and the support bars39 are to be provided.

Next, in the process illustrated in FIG. 4C, the photoresist 300 and thephotoresist 310 illustrated in FIG. 4B are removed. After removing thephotoresist 300 and the photoresist 310, a surface roughening processmay be performed, if necessary, on the upper surface and the lowersurface of the plate member 10A, including inner wall surfaces of thecavity part 10 y. The surface roughening process is not limited to aparticular roughening process. For example, the surface rougheningprocess may be an oxidation process, a blasting process, or the like. Byperforming the surface roughening process, it is possible to furtherimprove the adhesion between the plate member 10A and the first resin331.

Next, in the process illustrated in FIG. 4D, the resin part 33 in theform of a film and provided on a metal film 400, is prepared. The resinpart 33 has the multi-layer structure in which the second resin 332 andthe first resin 331 are successively stacked on the metal film 400. Atthis stage of the manufacturing process, the second resin 332 and thefirst resin 331 are in a B-stage state (semi-cured state). In a case inwhich surface roughnesses of upper and lower surfaces of the metal film400 are different, the resin part 33 is preferably provided on thesurface having the smaller surface roughness, in order to facilitateseparation of the metal film 400 from the resin part 33 at a later stageof the manufacturing process.

The metal film 400 may be a copper film having a thickness ofapproximately 12 μm to approximately 25 μm, for example. The first resin331 and the second resin 332 may be an epoxy resin, a polyimide resin,or the like, for example. The first resin 331 may have a thickness ofapproximately 10 μm to approximately 30 μm, for example. The secondresin 332 may have a thickness of approximately 30 μm to approximately50 μm, for example. The first resin 331 and the second resin 332 includea filler such as silica, alumina, or the like, for example. The amountof the filler included in the first resin 331 is smaller than the amountof the filler included in the second resin 332.

In the process illustrated in FIG. 4D, instead of the resin part 33 thatis formed by successively stacking the second resin 332 and the firstresin 331 on the metal film 400, it is possible to use a resin part 33that is formed by successively stacking the second resin 332 and thefirst resin 331 on a support film. In this case, the support film may bea resin film made of polyethylene terephthalate, polyethylene, or thelike, for example. In addition, the support film may have a thickness ofapproximately 30 μm to approximately 40 μm, for example. The supportfilm may be mechanically removed in the process illustrated in FIG. 5Dthat will be described later.

Next, as illustrated in FIG. 4E, the resin part 33 is adhered on thelower surface of the plate member 10A, and the cavity part 10 y isfilled by the resin part 33. More particularly, the metal film 400provided with the resin part 33 is arranged so that the first resin 331opposes the lower surface of the plate member 10A, and the plate member10A is pressed toward the metal film 400 in FIG. 4D. The first resin 331and the second resin 332 in the B-stage state are deformed inconformance with the shape of the cavity part 10 y, to fill the cavitypart 10 y. In this state, only the first resin 331 forming the upperlayer of the resin part 33 makes contact with the lower surface of theplate member 10A, including the inner wall surface of the cavity part 10y. Thereafter, the first resin 331 and the second resin 332 are heatedto a curing temperature or higher, to cure the first resin 331 and thesecond resin 332 and adhere the resin part 33 to the lower surface ofthe plate member 10A. The first resin 331 and the second resin 332 maybe heated while pressing the plate member 10A toward the metal film 400in FIG. 4D. Because the metal film 400 is provided on the lower surfaceof the resin part 33 opposite to the upper surface of the resin part 33to which the plate member 10A is adhered, it is possible to improve arigidity or strength of the product during the manufacturing process, toenable a stable process to be performed at subsequent stages of themanufacturing process.

Next, in the process illustrated in FIG. 5A, a photoresist 320 is formedon the entire upper surface of the plate member 10A, and a photoresist330 is formed on the entire lower surface of the metal film 400. Forexample, the photoresist 320 and the photoresist 330 may be made of adry film resist or the like. The photoresist 320 is exposed, developed,and patterned so as to expose the regions that are to be etched. In theplan view, the photoresist 320 is patterned so as to cover the regionswhere the die pad 31, the leads 32, the frame part 38, and the supportbars 39 illustrated in FIG. 2A are provided. In this state, thephotoresist 330 still covers the entire lower surface of the metal film400.

Next, in the process illustrated in FIG. 5B, the plate member 10A isetched using the resist 320 and the resist 330 as etching masks. Hence,a part of the region forming a bottom part of the cavity part 10 y inthe plate member 10A is removed, to form the planar-shaped die pad 31,the leads 32, the frame part 38, and the support bars 39 illustrated inFIG. 2A. In this state, the cutout part 311 is provided in the lowersurface 31 b of the die pad 31, and separates the cavity part 10 y. Inaddition, the cutout part 321 is provided in the lower surface 32 b ofthe lead 32, in the region of the lead 32 opposing the die pad 31, andseparates the cavity part 10 y.

In the case in which the plate member 10A is made of copper, the die pad31 including the cutout part 311, the leads 32 including the cutout part321, the frame part 38, and the support bars 39 may be formed by the wetetching using the cupric chloride solution, for example. Because thebottom part of the cavity part 10 y is made thin by the half-etchingperformed in the process illustrated in FIG. 4B, the wet etching can beperformed with ease, thereby making it possible to form the leads 32that are arranged at a narrow pitch. The pitch of the leads 32 may beapproximately 30 μm to approximately 70 μm, for example.

Next, in the process illustrated in FIG. 5C, the photoresist 320 and thephotoresist 330 illustrated in FIG. 5B are removed.

Next, in the process illustrated in FIG. 5D, the metal film 400 is firstremoved. The second resin 332 in contact with the metal film 400includes the large amount of the filler (large filler-content), andthus, the adhesion between the second resin 332 and the metal film 400is poor. For this reason, the metal film 400 can be mechanically removedfrom the second resin 332 with ease. Of course, the metal film 400 maybe removed by buffing, wet blasting, or the like. Similarly, the supportfilm used in place of the metal film 400 may be mechanically removed bysimilar methods.

After removing the metal film 400, the resin part 33 formed below thelower surface 31 b of the die pad 31 and the lower surfaces 32 b of theleads 32 is removed, to expose the lower surface 31 b of the die pad 31and the lower surfaces 32 b of the leads 32. For example, the lowersurface of the resin part 33, from which unwanted parts are removed, islocated on the same plane as the lower surface 31 b of the die pad 31and the lower surfaces 32 b of the leads 32. The unwanted parts of theresin part 33 may be removed by buffing, wet blasting, or the like, forexample.

In a case in which a buffing compound, an abrasive, or the like remainson the lower surface 31 b of the die pad 31 and on the lower surfaces 32b of the leads 32, a soft etching is preferably performed to remove theresidual buffing compound, abrasive, or the like on the lower surface 31b of the die pad 31 and on the lower surfaces 32 b of the leads. Thesoft etching refers to an etching that can uniformly etch a surface ofan object by a thickness of approximately several μm. In a case in whichthe die pad 31 and the leads 32 are made of copper, the soft etching canbe performed using the cupric chloride solution, for example. When thesoft etching is performed to remove the residual buffing compound,abrasive, or the like, the lower surface 31 b of the die pad 31 and thelower surfaces 32 b of the leads 32 cave in slightly from the lowersurface of the resin part 33.

Next, in the process illustrated in FIG. 6A, a photoresist 340 is formedon the upper surface 31 a of the die pad 31, the upper surfaces 32 a ofthe leads 32, the upper surface of the frame part 38, and the uppersurfaces of the support bars 39. Similarly, a photoresist 350 is formedon the lower surface 31 b of the die pad 31, the lower surfaces 32 b ofthe leads 32, and the lower surface of the resin part 33. For example,the photoresist 340 and the photoresist 350 may be made of a dry filmresist or the like. The photoresist 340 is exposed, developed, andpatterned so as to expose the regions where the metal layers 34 and 35are to be formed. In this state, the photoresist 350 still covers all ofthe lower surface 31 b of the die pad 31, the lower surfaces 32 b of theleads 32, and the lower surface of the resin part 33.

Next, in the process illustrated in FIG. 6B, the metal layer 34 isformed on the upper surface 31 a of the die pad 31 in the region notcovered by the photoresist 340. In addition, the metal layer 35 isformed on the upper surfaces 32 a of the leads 32 in the regions notcovered by the photoresist 340. The materials described above may beused for the metal layers 34 and 35. The metal layers 34 and 35 may beformed by electroplating, for example. The die pad 31 and the leads 32of each unit substrate 30 are electrically connected to each other viathe frame part 38 and the support bars 39. For this reason, the framepart 38 and the support bars 39 may be used as feed paths whenperforming the electroplating.

Next, in the process illustrated in FIG. 6C, the photoresist 340 and thephotoresist 350 illustrated in FIG. 6B are removed. Accordingly, thesubstrate 1 for semiconductor elements illustrated in FIG. 1, in whichthe unit substrates 30 are arranged in the matrix arrangement, iscompleted.

The manufacturing process of the semiconductor device, includingmounting of the semiconductor element on the unit substrate 30, will nowbe described, by referring to FIG. 7A through FIG. 7D. FIG. 7A, FIG. 7B,FIG. 7C, and FIG. 7D are diagrams illustrating examples of manufacturingprocesses of the semiconductor device in the first embodiment.

First, in the process illustrated in FIG. 7A, a semiconductor element 40in a face-up state is mounted on the upper surface 31 a of the die pad31 of each unit substrate 30. The semiconductor element 40 may bemounted on the upper surface 31 a of the die pad 31 through a conductivebonding material 50, such as silver paste or the like, by die bonding.

Next, in the process illustrated in FIG. 7B, electrode terminals 41formed on a circuit forming surface of the semiconductor element 40 areelectrically connected to the metal layers 34 and 35, via metal wires 60formed by gold wires, copper wires, or the like. The metal wires 60 canconnect the electrode terminals 41 of the semiconductor element 40 tothe metal layers 34 and 35 by wire bonding, for example.

Next, in the process illustrated in FIG. 7C, an encapsulating resin 70is formed to encapsulate each unit substrate 30, the semiconductorelement 40, and the metal wires 60. The encapsulating resin 70 may be aso-called mold resin formed by an insulating resin, such as an epoxyresin or the like, and including a filler, for example. Theencapsulating resin 70 may be molded by transfer molding, compressionmolding, or the like, for example. The encapsulating resin 70 isprovided on the upper surface of the unit substrate 30.

Next, in the process illustrated in FIG. 7D, a metal layer 36 forexternal connection is formed on the lower surfaces 32 b of the leads32, before cutting the unit substrates 30 into individual pieces. Themetal layer 36 may be made of the same metal material as the metallayers 34 and 35. For example, the metal layer 36 may be formed by a Snlayer.

When forming the metal layer 36, a photoresist is formed on the lowersurface 31 b of the die pad 31, the lower surfaces 32 b of the leads 32,and the lower surface of the resin part 33. The photoresist isthereafter exposed, developed, and patterned, so as to expose regionswhere the metal layer 36 is to be formed. Then, the metal layer 36 isfamed on the lower surfaces 32 b of the leads 32 in the regions notcovered by the photoresist, by electroplating using the frame part 38and the support bars 39 as the feed paths, for example. The photoresistis thereafter removed. The metal layer 36 may also be provided on thelower surface 31 b of the die pad 31. In this case, the electroplatingmay be performed by omitting the photoresist forming process, and ametal layer that is the same as the metal layer 36 may be formed on thelower surface 31 b of the die pad 31, simultaneously as the forming ofthe metal layer 36 on the lower surfaces 32 b of the leads 32.

After forming the metal layer 36, the unit substrates 30 are cut at thecutting positions C into the individual pieces, to complete a pluralityof semiconductor devices 2. The unit substrates 30 may be cut by aslicer or the like, for example. The electrode terminals 41 that areconnected to the metal layer 34 via the metal wires 60 may connect thedie pad 31 to ground GND, for example, to fix the die pad 31 to a groundpotential GND.

In the semiconductor device 2, the upper surface 31 a of the die pad 31and the side surfaces of the die pad 31 closer to the upper surface 31 aare covered by the encapsulating resin 70. In addition, the uppersurfaces 32 a of the leads 32 and the side surfaces of the leads 32closer to the upper surfaces 32 a are covered by the encapsulating resin70. Further, side surfaces of the leads 32 that are formed by cuttingthe unit substrates 30 are exposed at side surfaces of the encapsulatingresin 70 and at side surfaces of the resin part 33 that are respectivelyformed by cutting the unit substrates 30.

The semiconductor device 2 may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements illustrated inFIG. 1, in the state before being cut into the individual pieces, andincluding the unit substrates 30 illustrated in FIG. 2A through FIG. 2Cand FIG. 3, may be delivered as one product. In the latter case, thesubstrate 1 for semiconductor elements, delivered to a destination asone product, may be subjected to each of the processes described abovein conjunction with FIG. 7A through FIG. 7D at the destination tomanufacture the plurality of semiconductor devices 2.

First Modification of First Embodiment

In a first modification of the first embodiment, the substrate forsemiconductor elements is provided with a metal film on the lowersurface of the substrate for semiconductor elements. When describing thefirst modification of the first embodiment, a description of those partsthat are the same as those corresponding parts of the first embodimentmay be omitted.

FIG. 8A, FIG. 8B, and FIG. 8C are diagrams illustrating an example ofthe unit substrate forming the substrate for semiconductor elements inthe first modification of the first embodiment. FIG. 8A illustrates aplan view, FIG. 8B illustrates a cross section along a line A-A in FIG.8A, and FIG. 8C illustrates a cross section along a line B-B in FIG. 8A.

As illustrated in FIG. 8A through FIG. 8C, a unit substrate 30A differsfrom the unit substrate 30 illustrated in FIG. 2A through FIG. 2C, inthat a stacked structure made up of the metal film 400, the second resin332, and the first resin 331, is adhered to the lower surface 31 b ofthe die pad 31 and the lower surfaces 32 b of the leads 32.

In the unit substrate 30A, the resin part 33 is provided to fill theregions in which the die pad 31, the leads 32, the frame part 38, andthe support bars 39 are not provided in the plan view, similarly as inthe case of the unit substrate 30. In addition, the resin part 33 isprovided to fill the cutout parts 311 and 321, and to cover the lowersurfaces of the frame part 38 and the support bars 39 that arehalf-etched. However, unlike the unit substrate 30, the resin part 33 inthe unit substrate 30A covers the lower surface 31 b of the die pad 31and the lower surfaces 32 b of the leads 32.

More particularly, the second resin 332 is formed on the metal film 400,and the first resin 331 is formed on the second resin 332. The firstresin 331 extends from inside the cutout part 311 to the lower surface31 b of the die pad 31, to directly cover the entire lower surface 31 bof the die pad 31. In addition, the first resin 331 extends from insidethe cutout part 321 to the lower surfaces 32 b of the leads 32, todirectly cover the entire lower surfaces 32 b of the leads 32. Thesecond resin 332 is arranged to stretch over the first resin 331 thatextends from inside the cutout part 311, to directly cover the lowersurface 31 b of the die pad 31. In addition, the second resin 332 isarranged to stretch over the first resin 331 that extends from insidethe cutout part 321, to directly cover the lower surfaces 32 b of theleads 32.

FIG. 9A and FIG. 9B are diagrams illustrating examples of manufacturingprocesses of the substrate for semiconductor elements in the firstmodification of the first embodiment. FIG. 9A and FIG. 9B are crosssections corresponding to the cross section illustrated in FIG. 8B. Whenmanufacturing the substrate 1 for semiconductor elements, in which theunit substrates 30A are arranged in the matrix arrangement, processessimilar to the processes of the first embodiment described inconjunction with FIG. 4A through FIG. 5C are performed, to manufacture astacked structure illustrated in FIG. 9A.

Next, in the process illustrated in FIG. 9B, the metal layer 34 isformed in a predetermined region on the upper surface 31 a of the diepad 31, and the metal layer 35 is formed in predetermined regions on theupper surfaces 32 a of the leads 32, similarly to the processesdescribed in conjunction with FIG. 6A through FIG. 6C. Hence, thesubstrate 1 for semiconductor elements illustrated in FIG. 1, in whichthe unit substrates 30A are arranged in the matrix arrangement, iscompleted. In this modification of the first embodiment, a processcorresponding to the process illustrated in FIG. 5D is not performed inthe manufacturing process of the substrate 1 for semiconductor elements.

The manufacturing process of the semiconductor device, includingmounting of the semiconductor element on the unit substrate 30A, willnow be described, by referring to FIG. 10A through FIG. 10C. FIG. 10A,FIG. 10B, and FIG. 10C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the firstmodification of the first embodiment. First, processes similar to theprocesses of the first embodiment described in conjunction with FIG. 7Athrough 7C are performed, except that the unit substrate 30A is used inplace of the unit substrate 30, to manufacture a stacked structureillustrated in FIG. 10A.

In the process illustrated in FIG. 10B, the metal film 400 is removed bya process similar to the process described in conjunction with FIG. 5D.Then, the resin part 33 formed below the lower surface 31 b of the diepad 31 and the lower surfaces 32 b of the leads 32 is removed, to exposethe lower surface 31 b of the die pad 31 and the lower surfaces 32 b ofthe leads 32. For example, the lower surface of the resin part 33, fromwhich unwanted parts are removed, is located on the same plane as thelower surface 31 b of the die pad 31 and the lower surfaces 32 b of theleads 32.

Next, in the process illustrated in FIG. 10C, the metal layer 36 forexternal connection is formed on the lower surfaces 32 b of the leads32, and the unit substrates 30A are thereafter cut at the cuttingpositions C into the individual pieces, to complete a plurality ofsemiconductor devices 2A, similarly to the process described inconjunction with FIG. 7D. The semiconductor device 2A has the samestructure as the semiconductor device 2.

The semiconductor device 2A may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements, in the statebefore being cut into the individual pieces, and including the unitsubstrates 30A illustrated in FIG. 8A through FIG. 8C, may be deliveredas one product. In the latter case, the substrate 1 for semiconductorelements, delivered to the destination as one product, may be subjectedto each of the processes described above in conjunction with FIG. 10Athrough FIG. 10C at the destination to manufacture the plurality ofsemiconductor devices 2A.

By maintaining the metal film 400 on the unit substrate 30A until thelatter stages of the manufacturing process of the semiconductor device2A, it is possible to improve the rigidity or strength of the productduring the manufacturing process, to enable a stable process to beperformed at each stage of the manufacturing process.

Second Modification of First Embodiment

In a second modification of the first embodiment, the substrate forsemiconductor elements is provided with another resin part. Whendescribing the second modification of the first embodiment, adescription of those parts that are the same as those correspondingparts of the first embodiment and the first modification of the firstembodiment may be omitted.

FIG. 11A through FIG. 11C are diagrams illustrating an example of theunit substrate forming the substrate for semiconductor elements in thesecond modification of the first embodiment. FIG. 11A illustrates a planview, FIG. 11B illustrates a cross section along a line A-A in FIG. 11A,and FIG. 11C illustrates a cross section along a line B-B in FIG. 11A.

As illustrated in FIG. 11A through FIG. 11C, a unit substrate 30Bdiffers from the unit substrate 30A illustrated in FIG. 8A through FIG.8C, in that the unit substrate 30B includes another resin part 37. Theresin part 37 is formed on regions of the resin part 33 where the diepad 31, the leads 32, the frame part 38, and the support bars 39 are notprovided.

In the plan view, the resin part 37 is provided on the upper surface ofthe resin part 33 so as to fill the regions where the die pad 31, theleads 32, the frame part 38, and the support bars 39 are not provided.More particularly, the resin part 37 has a multi-layer structure, or alaminated structure, including a third resin 371 and a fourth resin 372.The third resin 371 is arranged to make contact with the side surfacesof the die pad 31 exposed from the resin part 33, the side surfacesalong the longitudinal direction of the leads 32 exposed from the resinpart 33, the end surfaces of the leads 32 opposing the die pad 31 andexposed from the resin part 33, the inner sidewalls of the frame part38, the side surfaces of the support bars 39, and the upper surface ofthe first resin 331.

In addition, the fourth resin 372 is arranged to sandwich the thirdresin 371 between the fourth resin 372 and each of the side surfaces ofthe die pad 31 exposed from the resin part 33, the side surfaces alongthe longitudinal direction of the leads 32 exposed from the resin part33, the end surfaces of the leads 32 opposing the die pad 31 and exposedfrom the resin part 33, the inner sidewalls of the frame part 38, theside surfaces of the support bars 39, and the upper surface of the firstresin 331. The resin part 37 exposes the upper surface 31 a of the diepad 31, the upper surfaces 32 a of the leads 32, the upper surface ofthe frame part 38, and the upper surfaces of the support bars 39.

The third resin 371 and the fourth resin 372 may be made of a materialsuch as an epoxy resin, a polyimide resin, or the like. The third resin371 and the fourth resin 372 include a filler, such as silica, alumina,or the like, for example. An amount of the filler included in the thirdresin 371 is smaller than an amount of the filler included in the fourthresin 372. A type of the filler included in the third resin 371 may bethe same as, or may be different from, a type of the filler included inthe fourth resin 372.

By reducing the amount of the filler included in the third resin 371 incontact with the die pad 31, the leads 32, the frame part 38, and thesupport bars 39, it is possible to increase a contact area of a resinpart (part excluding the filler) forming the third resin 371 and the diepad 31, the leads 32, the frame part 38, and the support bars 39. Forthis reason, it is possible to improve the adhesion of the third resin371 with respect to the die pad 31, the leads 32, the frame part 38, andthe support bars 39.

On the other hand, by increasing the amount of the filler included inthe fourth resin 372, it is possible to easily adjust the coefficient ofthermal expansion of the resin part 37. For example, when the amount ofthe filler included in the fourth resin 372 is adjusted so that thecoefficient of thermal expansion of the resin part 37 becomesapproximately the same as the coefficients of expansion of the die pad31, the leads 32, the frame part 38, and the support bars 39, it ispossible to reduce warping of the substrate 1 for semiconductorelements.

FIG. 12A, FIG. 12B, and FIG. 12C are diagrams illustrating examples ofmanufacturing processes of the substrate for semiconductor elements inthe second modification of the first embodiment. FIG. 12A through FIG.12C are cross sections corresponding to the cross section illustrated inFIG. 11B. When manufacturing the substrate 1 for semiconductor elements,in which the unit substrates 30B are arranged in the matrix arrangement,processes similar to the processes of the first embodiment described inconjunction with FIG. 4A through FIG. 5C are performed, to manufacture astacked structure illustrated in FIG. 9A.

Next, in the process illustrated in FIG. 12A, the resin part 37,provided on a metal film 450, is prepared. The resin part 37 has themulti-layer structure in which the fourth resin 372 and the third resin371 are successively stacked on the metal film 450. At this stage of themanufacturing process, the fourth resin 372 and the third resin 371 arein the B-stage state (semi-cured state). In a case in which surfaceroughnesses of upper and lower surfaces of the metal film 450 aredifferent, the resin part 37 is preferably provided on the surfacehaving the smaller surface roughness, in order to facilitate separationof the metal film 450 from the resin part 37 at a later stage of themanufacturing process.

The metal film 450 may be a copper film having a thickness ofapproximately 12 μm to approximately 25 μm, for example. The third resin371 and the fourth resin 372 may be an epoxy resin, a polyimide resin,or the like, for example. The third resin 371 may have a thickness ofapproximately 10 μm to approximately 30 μm, for example. The fourthresin 372 may have a thickness of approximately 30 μm to approximately50 μm, for example. The third resin 371 and the fourth resin 372 includea filler such as silica, alumina, or the like, for example. The amountof the filler included in the third resin 371 is smaller than the amountof the filler included in the fourth resin 372.

Next, the resin part 37 is adhered on the upper surface 31 a of the diepad 31, the upper surfaces 32 a of the leads 32, the upper surface ofthe frame part 38, and the upper surfaces of the support bars 39. Inaddition, the resin part 37 fills the regions on the resin part 33 wherethe die pad 31, the leads 32, the frame part 38, and the support bars 39are not provided. More particularly, the metal film 450 on which theresin part 37 is stacked, is arranged so that the third resin 371opposes the upper surface 31 a of the die pad 31, the upper surfaces 32a of the leads 32, the upper surface of the frame part 38, and the uppersurfaces of the support bars 39, and the metal film 450 is pressedtoward the metal film 400. The third resin 371 and the fourth resin 372in the B-stage state are deformed to fill the regions on the resin part33 where the die pad 31, the leads 32, the frame part 38, and thesupport bars 39 are not provided.

In this state, only the third resin 371 forming the upper layer of theresin part 37 makes contact with the side surfaces of the die pad 31exposed from the resin part 33, the side surfaces along the longitudinaldirection of the leads 32 exposed from the resin part 33, the endsurfaces of the leads 32 opposing the die pad 31 and exposed from theresin part 33, the inner sidewalls of the frame part 38, the sidesurfaces of the support bars 39, and the upper surface of the firstresin 331. Thereafter, the third resin 371 and the fourth resin 372 arecured by being heated to the curing temperature or higher. The thirdresin 371 and the fourth resin 372 may be heated while pressing themetal film 450 against the metal layer 400.

Next, in the process illustrated in FIG. 12B, the metal film 450 isfirst removed. Because the amount of the filler included in the fourthresin 372 in contact with the metal film 450 is large, the adhesionbetween the fourth resin 372 and the metal film 450 is poor. For thisreason, the metal film 450 can be mechanically removed from the fourthresin 372 with ease. Of course, the metal film 450 may be removed bybuffing, wet blasting, or the like.

After removing the metal film 450, the resin part 37 formed on the uppersurface 31 a of the die pad 31, the upper surfaces 32 a of the leads 32,the upper surface of the frame part 38, and the upper surfaces of thesupport bars 39 is removed, to expose the upper surface 31 a of the diepad 31, the upper surfaces 32 a of the leads 32, the upper surface ofthe frame part 38, and the upper surfaces of the support bars 39. Forexample, the upper surface of the resin part 37, from which unwantedparts are removed, is located on the same plane as the upper surface 31a of the die pad 31, the upper surfaces 32 a of the leads 32, the uppersurface of the frame part 38, and the upper surfaces of the support bars39. The resin part 37 may be removed by buffing, wet blasting, or thelike, similarly as in the case of the process described in conjunctionwith FIG. 5D.

In a case in which the buffing compound, the abrasive, or the likeremains on the upper surface 31 a of the die pad 31, the upper surfaces32 a of the leads 32, the upper surface of the frame part 38, and theupper surfaces of the support bars 39, the soft etching is preferablyperformed to remove the residual buffing compound, abrasive, or the likeon the upper surface 31 a of the die pad 31, the upper surfaces 32 a ofthe leads 32, the upper surface of the frame part 38, and the uppersurfaces of the support bars 39. In the case in which the die pad 31,the leads 32, the frame part 38, and the support bars 39 are made ofcopper, the soft etching can be performed using the cupric chloridesolution, for example. When the soft etching is performed to remove theresidual buffing compound, abrasive, or the like, the upper surface 31 aof the die pad 31, the upper surfaces 32 a of the leads 32, the uppersurface of the frame part 38, and the upper surfaces of the support bars39 cave in slightly from the upper surface of the resin part 37.

Next, in the process illustrated in FIG. 12C, the metal layer 34 isformed in the predetermined region on the upper surface 31 a of the diepad 31, and the metal layer 35 is formed in the predetermined regions onthe upper surfaces 32 a of the leads 32, similarly to the processesdescribed in conjunction with FIG. 6A through FIG. 6C. Hence, thesubstrate 1 for semiconductor elements illustrated in FIG. 1, in whichthe unit substrates 30B are arranged in the matrix arrangement, iscompleted.

The manufacturing process of the semiconductor device, includingmounting of the semiconductor element on the unit substrate 30B, willnow be described, by referring to FIG. 13A through FIG. 13C. FIG. 13A,FIG. 13B, and FIG. 13C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the secondmodification of the first embodiment. First, processes similar to theprocesses of the first embodiment described in conjunction with FIG. 7Athrough 7C are performed, except that the unit substrate 30B is used inplace of the unit substrate 30, to manufacture a stacked structureillustrated in FIG. 13A.

Next, in the process illustrated in FIG. 13B, the metal film 400 isremoved by a process similar to the process described in conjunctionwith FIG. 5D. Then, the resin part 33 formed below the lower surface 31b of the die pad 31 and the lower surfaces 32 b of the leads 32 isremoved. For example, the lower surface of the resin part 33, from whichunwanted parts are removed, is located on the same plane as the lowersurface 31 b of the die pad 31 and the lower surfaces 32 b of the leads32.

Next, in the process illustrated in FIG. 13C, the metal layer 36 forexternal connection is formed on the lower surfaces 32 b of the leads32, and the unit substrates 30B are thereafter cut at the cuttingpositions C into the individual pieces, to complete a plurality ofsemiconductor devices 2B, similarly to the process described inconjunction with FIG. 7D.

The semiconductor device 2B may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements, in the statebefore being cut into the individual pieces, and including the unitsubstrates 30B illustrated in FIG. 11A through FIG. 11C, may bedelivered as one product. In the latter case, the substrate 1 forsemiconductor elements, delivered to the destination as one product, maybe subjected to each of the processes described above in conjunctionwith FIG. 13A through FIG. 13C at the destination to manufacture theplurality of semiconductor devices 2B.

By filling the resin part 37 into the regions on the resin part 33 wherethe die pad 31, the leads 32, the frame part 38, and the support bars 39are not provided, it is possible to improve the rigidity or strength ofthe product during the manufacturing process, and further reduce warpingof the substrate 1 for semiconductor elements.

In addition, by maintaining the metal film 400 on the unit substrate 30Buntil the latter stages of the manufacturing process of thesemiconductor device 2B, it is possible to improve the rigidity orstrength of the product during the manufacturing process, to enable astable process to be performed at each stage of the manufacturingprocess.

After the process illustrated in FIG. 12C, the metal film 400 may beremoved, and the resin part 33 formed below the lower surface 31 b ofthe die pad 31 and the lower surfaces 32 b of the leads 32 may beremoved, as illustrated in FIG. 14, similarly as in the case of thefirst embodiment. In this case, the metal film 400 is not providedduring the manufacturing process of the semiconductor device 2B.However, the stable process can be performed at each stage of themanufacturing process because the rigidity or strength of the product isimproved by the provision of the resin part 37.

Third Modification of First Embodiment

In a third modification of the first embodiment, the substrate forsemiconductor elements is provided with a plurality of metal layers onthe upper surface of the die pad. When describing the third modificationof the first embodiment, a description of those parts that are the sameas those corresponding parts of the first embodiment may be omitted.

FIG. 15A through FIG. 15C are diagrams illustrating an example of theunit substrate forming the substrate for semiconductor elements in thethird modification of the first embodiment. FIG. 15A illustrates a planview, FIG. 15B illustrates a cross section along a line A-A in FIG. 15A,and FIG. 15C illustrates a cross section along a line B-B in FIG. 15A.

As illustrated in FIG. 15A through FIG. 15C, a unit substrate 30Cdiffers from the unit substrate 30 illustrated in FIG. 2A through FIG.2C, in that the unit substrate 30C includes a plurality of metal layers34A formed on the upper surface 31 a of the die pad 31.

The plurality of metal layers 34A are arranged vertically andhorizontally, in an area array, on the upper surface 31 a of the die pad31. The unit substrate 30C may be manufactured by processes similar tothe processes of the first embodiment described in conjunction with FIG.4A through FIG. 6C. However, in the process illustrated in FIG. 6A, thephotoresist 340 is patterned in correspondence with the regions wherethe metal films 34A illustrated in FIG. 15A are formed. The metal layers34A may be made of the same metal material as the metal layer 34, forexample. The metal layers 34A and the metal layer 35 may be used as padsfor flip-chip bonding to the electrodes of the semiconductor element viasolder bumps or the like.

The manufacturing process of the semiconductor device, includingmounting of the semiconductor element on the unit substrate 30C, willnow be described, by referring to FIG. 16A through FIG. 16C. FIG. 16A,FIG. 16B, and FIG. 16C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the thirdmodification of the first embodiment. First, in the process illustratedin FIG. 16A, the semiconductor element 40 in a face-down state ismounted on each unit substrate 30C. More particularly, the electrodeterminals 41 formed on the circuit forming surface of the semiconductorelement 40 are electrically connected to the metal layers 34A and 35,via solder bumps 80.

Next, in the process illustrated in FIG. 16B, the encapsulating resin 70is formed to encapsulate each unit substrate 30C, the semiconductorelement 40, and the solder bumps 80 by a process similar to the processdescribed in conjunction with in FIG. 7C. The encapsulating resin 70 maybe formed to expose a back surface of the semiconductor element 40. Inaddition, an underfill resin may fill spaces between the semiconductorelement 40 and the unit substrate 30C, before forming the encapsulatingresin 70.

Next, in the process illustrated in FIG. 16C, the metal layer 36 forexternal connection is formed on the lower surfaces 32 b of the leads32, and the unit substrates 30C are thereafter cut at the cuttingpositions C into the individual pieces, to complete a plurality ofsemiconductor devices 2C, similarly to the process described inconjunction with FIG. 7D. The electrode terminals 41 that are connectedto the metal layer 34A via the solder bumps 80 may be fixed to theground potential GND, by connecting the die pad 31 to the ground GND,for example.

The semiconductor device 2C may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements, in the statebefore being cut into the individual pieces, and including the unitsubstrates 30C illustrated in FIG. 15A through FIG. 15C, may bedelivered as one product. In the latter case, the substrate 1 forsemiconductor elements, delivered to the destination as one product, maybe subjected to each of the processes described above in conjunctionwith FIG. 16A through FIG. 16C at the destination to manufacture theplurality of semiconductor devices 2C.

According to this modification, it is possible to manufacture thesemiconductor device 2C in which the semiconductor element 40 isflip-chip bonded on the unit substrate 30C.

Similarly as in the case of the first modification of the firstembodiment, the stacked structure made up of the metal film 400, thesecond resin 332, and the first resin 331, may be adhered to the lowersurface 31 b of the die pad 31 and the lower surfaces 32 b of the leads32. In this case, in the manufacturing process of the semiconductordevice 2C, the resin part 33 formed below the lower surface 31 b of thedie pad 31 and the lower surfaces 32 b of the leads 32 is removed afterremoving the metal film 400.

Fourth Modification of First Embodiment

In a fourth modification of the first embodiment, the substrate forsemiconductor elements is not provided with the die pad, the supportbars, or the like. When describing the fourth modification of the firstembodiment, a description of those parts that are the same as thosecorresponding parts of the first embodiment and the modificationsthereof may be omitted.

FIG. 17A through FIG. 17C are diagrams illustrating an example of theunit substrate forming the substrate for semiconductor elements in thefourth modification of the first embodiment. FIG. 17A illustrates a planview, FIG. 17B illustrates a cross section along a line A-A in FIG. 17A,and FIG. 17C illustrates a cross section along a line B-B in FIG. 17A.

As illustrated in FIG. 17A through FIG. 17C, a unit substrate 30Ddiffers from the unit substrate 30C illustrated in FIG. 15A through FIG.15C, in that the unit substrate 30D is not provided with the die pad 31,the metal layers 34A, and the support bars 39. Because the unitsubstrate 30D includes no die pad 31, no cutout part 311 is provided. Inaddition, the resin part 33 fills the region where the lower surface 31b of the die pad 31 is arranged in the unit substrate 30C.

FIG. 18 is a diagram illustrating an example of a manufacturing processof the substrate for semiconductor elements in the fourth modificationof the first embodiment. FIG. 18 illustrates a cross sectioncorresponding to the cross section illustrated in FIG. 17B. Whenmanufacturing the substrate 1 for semiconductor elements, in which theunit substrates 30D are arranged in the matrix arrangement, a processsimilar to the process described in conjunction with FIG. 16A isperformed, to mount the semiconductor element 40 in the face-down stateon each unit substrate 30D. More particularly, the electrode terminals41 formed on the circuit forming surface of the semiconductor element 40are electrically connected to the metal layer 35, via the solder bumps80.

Next, the encapsulating resin 70 is formed to encapsulate each unitsubstrate 30D, the semiconductor element 40, and the solder bumps 80 bya process similar to the process described in conjunction with FIG. 16B.The encapsulating resin 70 may be formed to expose the back surface ofthe semiconductor element 40. In addition, the underfill resin may fillspaces between the semiconductor element 40 and the unit substrate 30D,before forming the encapsulating resin 70.

Next, in the process illustrated in FIG. 18, the metal layer 36 forexternal connection is formed on the lower surfaces 32 b of the leads32, and the unit substrates 30D are thereafter cut at the cuttingpositions C into the individual pieces, to complete a plurality ofsemiconductor devices 2D, similarly to the process described inconjunction with FIG. 16C.

The semiconductor device 2D may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements, in the statebefore being cut into the individual pieces, and including the unitsubstrates 30D illustrated in FIG. 17A through FIG. 17C, may bedelivered as one product. In the latter case, the substrate 1 forsemiconductor elements, delivered to the destination as one product, maybe subjected to the processes including the process described above inconjunction with FIG. 18 or the like at the destination to manufacturethe plurality of semiconductor devices 2D.

According to this modification, it is possible to manufacture thesemiconductor device 2D in which the semiconductor element 40 isflip-chip bonded on the unit substrate 30D.

Fifth Modification of First Embodiment

In a fifth modification of the first embodiment, the substrate forsemiconductor elements is not provided with the frame part and thesupport bars. When describing the fifth modification of the firstembodiment, a description of those parts that are the same as thosecorresponding parts of the first embodiment and the modificationsthereof may be omitted.

FIG. 19A through FIG. 19C are diagrams illustrating an example of theunit substrate forming the substrate for semiconductor elements in thefifth modification of the first embodiment. FIG. 19A illustrates a planview, FIG. 19B illustrates a cross section along a line A-A in FIG. 19A,and FIG. 19C illustrates a cross section along a line B-B in FIG. 19A.

As illustrated in FIG. 19A through FIG. 19C, a unit substrate 30Ediffers from the unit substrate 30 illustrated in FIG. 2A through FIG.2C, in that the unit substrate 30E is not provided with the frame part38 and the support bars 39.

FIG. 20A, FIG. 20B, FIG. 20C, and FIG. 20D are diagrams illustratingexamples of manufacturing processes of the substrate for semiconductorelements in the fifth modification of the first embodiment. FIG. 20Athrough FIG. 20D illustrate cross sections corresponding to the crosssection illustrated in FIG. 19B. When manufacturing the substrate 1 forsemiconductor elements, in which the unit substrates 30E are arranged inthe matrix arrangement, processes similar to the processes of the firstembodiment described in conjunction with FIG. 4A through FIG. 4E areperformed. Then, without performing the processes described inconjunction with FIG. 5A through FIG. 5D, processes similar to theprocesses of the first embodiment described in conjunction with FIG. 6Athrough 6C are performed, to manufacture a stacked structure illustratedin FIG. 20A. The metal layers 34 and 35 may be formed by electroplatingusing the plate member 10A as the feed path, for example.

Next, in the process illustrated in FIG. 20B, a photoresist 360 isformed on the entire upper surface of the plate member 10A, and aphotoresist 370 is formed on the entire lower surface of the metal film400. For example, the photoresist 360 and the photoresist 370 may bemade of a dry film resist or the like. The photoresist 360 is exposed,developed, and patterned so as to expose the regions that are to beetched. In the plan view, the photoresist 360 is patterned so as tocover the regions where the die pad 31 and the leads 32 are provided. Inthis state, the photoresist 370 still covers the entire lower surface ofthe metal film 400.

Next, in the process illustrated in FIG. 20C, the plate member 10A isetched using the photoresist 360 and the photoresist 370 as etchingmasks. Hence, a part of the region forming the bottom of the cavity part10 y of the plate member 10A is removed, and the die pad 31 and theleads 32 having the planar shape illustrated in FIG. 19A are formed. Inthis state, the cutout part 311 is provided in the lower surface 31 b ofthe die pad 31, and separates the cavity part 10 y. In addition, thecutout part 321 is provided in the lower surface 32 b of the lead 32, inthe region of the lead 32 opposing the die pad 31, and separates thecavity part 10 y.

In the case in which the plate member 10A is made of copper, the die pad31 including the cutout part 311, and the leads 32 including the cutoutpart 321, the frame part 38 may be formed by the wet etching using thecupric chloride solution, for example. Parts corresponding to the framepart 38 and the support bars 39 illustrated in FIG. 2A through FIG. 2Care also etched, so that the die pad 31 and the leads 32 are supportedsolely by the resin part 33.

Next, in the process illustrated in FIG. 20D, the resist 360 and theresist 370 illustrated in FIG. 20C are removed. After the processillustrated in FIG. 20D, the metal film 400 is removed by a processsimilar to the process described in conjunction with FIG. 5D. Then, theresin part 33 formed below the lower surface 31 b of the die pad 31 andthe lower surfaces 32 b of the leads 32 is removed, to expose the lowersurface 31 b of the die pad 31 and the lower surfaces 32 b of the leads32, and complete the substrate 1 for semiconductor elements illustratedin FIG. 1 in which the unit substrates 30E are arranged in the matrixarrangement.

The manufacturing process of the semiconductor device, includingmounting of the semiconductor element on the unit substrate 30E, willnow be described, by referring to FIG. 21A and FIG. 21B. First,processes similar to the processes of the first embodiment described inconjunction with FIG. 7A through 7C are performed, except that the unitsubstrate 30E is used in place of the unit substrate 30, to manufacturea stacked structure illustrated in FIG. 21A.

In the process illustrated in FIG. 21B, the metal layer 36 for externalconnection is formed on the lower surfaces 32 b of the leads 32, and theunit substrates 30E are thereafter cut at the cutting positions C intothe individual pieces, to complete a plurality of semiconductor devices2E, similarly to the process described in conjunction with FIG. 7D. Themetal layer 36 may be formed by electroplating, for example. In thesemiconductor device 2E, the lower part of the side surfaces of theleads 32 are covered by the resin part 33, and the upper part of theside surfaces of the leads 32 are covered by the encapsulating resin 70.Thus, the side surfaces of the leads 32 are not exposed to the outside.

The semiconductor device 2E may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements, in the statebefore being cut into the individual pieces, and including the unitsubstrates 30E illustrated in FIG. 19A through FIG. 19C, may bedelivered as one product. In the latter case, the substrate 1 forsemiconductor elements, delivered to the destination as one product, maybe subjected to processes including the process described above inconjunction with FIG. 18 at the destination to manufacture the pluralityof semiconductor devices 2E.

The unit substrate does not need to be provided with the frame part andthe support bars, as in the case of this modification. In this case, thesubstrate 1 for semiconductor elements can be manufacturedsatisfactorily, because the die pad 31 and the leads 32 can be supportedby the resin part 33.

Sixth Modification of First Embodiment

A sixth modification of the first embodiment is another example in whichthe substrate for semiconductor elements is not provided with the framepart and the support bars. When describing the sixth modification of thefirst embodiment, a description of those parts that are the same asthose corresponding parts of the first embodiment and the modificationsthereof may be omitted.

FIG. 22A through FIG. 22C are diagrams illustrating an example of theunit substrate forming the substrate for semiconductor elements in thesixth modification of the first embodiment. FIG. 22A illustrates a planview, FIG. 22B illustrates a cross section along a line A-A in FIG. 22A,and FIG. 22C illustrates a cross section along a line B-B in FIG. 22A.

As illustrated in FIG. 22A through FIG. 22C, a unit substrate 30Fdiffers from the unit substrate 30A illustrated in FIG. 8A through FIG.8C, in that the unit substrate 30F is not provided with the frame part38 and the support bars 39.

The unit substrate 30F may be manufactured by the processes of the fifthmodification of the first embodiment described in conjunction with FIG.20A through FIG. 20D. In this modification, however, the processillustrated in FIG. 20D becomes a last process, and there is no processof removing the metal film 400 and the resin part 33 after the processillustrated in FIG. 20D.

The manufacturing process of the semiconductor device, includingmounting of the semiconductor element on the unit substrate 30F, willnow be described, by referring to FIG. 23A through FIG. 23C. FIG. 23A,FIG. 23B, and FIG. 23C are diagrams illustrating examples ofmanufacturing processes of the semiconductor device in the sixthmodification of the first embodiment. First, processes similar to theprocesses of the first embodiment described in conjunction with FIG. 7Athrough 7C are performed, except that the unit substrate 30F is used inplace of the unit substrate 30, to manufacture a stacked structureillustrated in FIG. 23A.

In the process illustrated in FIG. 23B, the metal film 400 is removed bya process similar to the process described in conjunction with FIG. 5D.Then, the resin part 33 formed below the lower surface 31 b of the diepad 31 and the lower surfaces 32 b of the leads 32 is removed, to exposethe lower surface 31 b of the die pad 31 and the lower surfaces 32 b ofthe leads 32. For example, the lower surface of the resin part 33, fromwhich unwanted parts are removed, is located on the same plane as thelower surface 31 b of the die pad 31 and the lower surfaces 32 b of theleads 32.

Next, in the process illustrated in FIG. 23C, the metal layer 36 forexternal connection is formed on the lower surfaces 32 b of the leads32, and the unit substrates 30F are thereafter cut at the cuttingpositions C into the individual pieces, to complete a plurality ofsemiconductor devices 2F, similarly to the process described inconjunction with FIG. 7D. The semiconductor device 2F has the samestructure as the semiconductor device 2E. The metal layer 36 may beformed by electroplating, for example. In the semiconductor device 2F,the lower part of the side surfaces of the leads 32 are covered by theresin part 33, and the upper part of the side surfaces of the leads 32are covered by the encapsulating resin 70. Thus, the side surfaces ofthe leads 32 are not exposed to the outside.

The semiconductor device 2F may be delivered as one product.Alternatively, the substrate 1 for semiconductor elements, in the statebefore being cut into the individual pieces, and including the unitsubstrates 30F illustrated in FIG. 22A through FIG. 22C, may bedelivered as one product. In the latter case, the substrate 1 forsemiconductor elements, delivered to the destination as one product, maybe subjected to each of the processes described above in conjunctionwith FIG. 23A through FIG. 23C at the destination to manufacture theplurality of semiconductor devices 2F.

The unit substrate does not need to be provided with the frame part andthe support bars, as in the case of this modification. In this case, thesubstrate 1 for semiconductor elements can be manufacturedsatisfactorily, because the die pad 31 and the leads 32 can be supportedby the resin part 33. In addition, by maintaining the metal film 400 onthe unit substrate 30F until the latter stages of the manufacturingprocess of the semiconductor device 2F, it is possible to improve therigidity or strength of the product during the manufacturing process, toenable a stable process to be performed at each stage of themanufacturing process.

Second Embodiment

In a second embodiment, the unit substrate 30C of the third modificationof the first embodiment has a structure similar to that of the fifth orsixth modification of the first embodiment, including no frame part andno support bars. In this embodiment, the semiconductor element can beflip-chip bonded to the unit substrate having no frame part and nosupport bars.

Third Embodiment

In a third embodiment, the unit substrate 30D of the fourth modificationof the first embodiment has a structure similar to that of the fifth orsixth modification of the first embodiment, including no frame part.

Fourth Embodiment

In a fourth embodiment, the substrate 1 for semiconductor elements inany of the third through sixth modifications of the first embodiment isadditionally provided with the other resin part of the secondmodification of the first embodiment.

Although the embodiments and the modifications are numbered with, forexample, “first,” “second,” or “third,” etc., the ordinal numbers do notimply priorities of the embodiments. Many other variations andmodifications will be apparent to those skilled in the art.

According to the embodiments and the modifications, it is possible toimprove the adhesion between the resin and the metal in the substratefor semiconductor elements, and to reduce warping of the substrate forsemiconductor elements.

Various aspects of the subject matter described herein may be set outnon-exhaustively in the following numbered clauses:

1. A method of manufacturing a substrate for semiconductor elements,comprising:

half-etching a metal plate having one surface and an opposite surfaceopposite to the one surface, to form a cavity part that caves in fromthe opposite surface toward the one surface;

arranging a resin part having a multi-layer structure including a firstresin and a second resin that are in a semi-cured state, so that thefirst resin opposes the opposite surface of the metal plate, andadhering the resin part to the opposite surface of the metal plate tofill a bottom part of the cavity part with the resin part; and

forming a terminal part having a first surface, a second surfaceopposite to the first surface, and side surfaces by curing the resinpart and thereafter partially removing the resin part in a regionforming the bottom part of the cavity part in the metal plate,

wherein the forming forms the terminal part so that the first surface isexposed from the resin part, the side surfaces are covered by the resinpart, and the first resin contacts the side surfaces of the terminalpart, and

wherein the first resin and the second resin include a filler, and anamount of the filler included in the first resin is smaller than anamount of the filler included in the second resin.

2. The method of manufacturing the substrate for semiconductor elementsaccording to clause 1, further comprising:

preparing the resin part including the second resin and the first resinthat are in the semi-cured state and are successively stacked on one ofa metal film and a support film.

3. The method of manufacturing the substrate for semiconductor elementsaccording to clause 1 or 2, wherein the forming forms a semiconductorelement mounting part together with the terminal part, and furthercomprising:

forming a first cutout part in the other surface at an outer peripheralpart of the semiconductor element mounting part, and separating thecavity part; and

forming a second cutout part in the second surface at an end part of theterminal part, facing the outer peripheral part of the semiconductorelement mounting part, and separating the cavity part.

4. The method of manufacturing the substrate for semiconductor elementsaccording to clause 3, further comprising:

arranging another resin part having a multi-layer structure including athird resin and a fourth resin, so that the third resin opposes onesurface of the semiconductor element mounting part and the first surfaceof the terminal part, and adhering the third resin to the one surface ofthe semiconductor element mounting part and the first surface of theterminal part, to fill a region on the resin part where thesemiconductor element mounting part and the terminal part are notprovided with the other resin part; and

removing the other resin part formed above the one surface of thesemiconductor element mounting part and the first surface of theterminal part, to expose the one surface of the semiconductor elementmounting part and the first surface of the terminal part.

5. The method of manufacturing the substrate for semiconductor elementsaccording to clause 3 or 4, further comprising:

after forming the semiconductor element mounting part together with theterminal part, removing the resin part below the other surface of thesemiconductor element mounting part and the second surface of theterminal part, to expose the other surface of the semiconductor elementmounting part and the second surface of the terminal part.

6. A method of manufacturing a semiconductor device, comprising:

forming the substrate for semiconductor elements according to any ofclauses 1 to 5;

mounting a semiconductor element on one surface of the substrate forsemiconductor elements;

forming an encapsulating resin on the one surface of the substrate forsemiconductor elements, to encapsulate the semiconductor element; and

removing the resin part formed below the second surface of the terminalpart, to expose the second surface of the terminal part.

The description above use terms such as “determine”, or the like todescribe the embodiments, however, such terms are abstractions of theactual operations that are performed. Hence, the actual operations thatcorrespond to such taws may vary depending on the implementation, as isobvious to those skilled in the art.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

What is claimed is:
 1. A substrate for semiconductor elements,comprising: a plurality of leads respectively including a first surface,a second surface opposite to the first surface, side surfaces joiningthe first surface and the second surface, a first end, and a second endopposite to the first end; a cutout part provided in the second surfaceat the first end of each of the plurality of leads; an externalconnection part provided on the second surface at the second end of eachof the plurality of leads, wherein each of the plurality of leads has afirst thickness at the cutout part thinner than a second thickness atthe external connection part; and a resin part covering the sidesurfaces and exposing the first surface of each of the plurality ofleads, and filling an inside of the cutout part, wherein the resin parthas a multi-layer structure, including a first resin and a second resin,and having the first resin laminated on the second resin, wherein thefirst resin is provided in contact with the side surfaces of each of theplurality of leads and an inner wall surface of the cutout part, whereinthe first resin and the second resin include a filler, and wherein anamount of the filler included in the first resin is smaller than anamount of the filler included in the second resin.
 2. The substrate forsemiconductor elements as claimed in claim 1, further comprising: asemiconductor element mounting part including a third surface on which asemiconductor element is mounted, a fourth surface opposite to the thirdsurface, and a first cutout part provided in the fourth surface at anouter peripheral part of the semiconductor element mounting part,wherein each of the plurality of leads is arranged at a positionseparated from the semiconductor element mounting part, and includes asecond cutout part provided in the second surface at the first end ofeach of the plurality of leads facing the outer peripheral part of thesemiconductor element mounting part, wherein the resin part holds thesemiconductor element mounting part and the plurality of leads in astate in which the third surface of the semiconductor element mountingpart and the first surface of each of the plurality of leads areexposed, and fills the first cutout part and the second cutout part, andwherein the first resin is arranged to make contact with inner wallsurfaces of the first cutout part and inner wall surfaces of the secondcutout part.
 3. The substrate for semiconductor elements as claimed inclaim 2, wherein the first resin extends from inside the first cutoutpart toward a part of a side surface of the semiconductor elementmounting part, to directly cover the part of the side surface of thesemiconductor element mounting part, and also extends from inside thesecond cutout part toward a part of the side surfaces of each of the ofleads, to directly cover the part of the side surfaces of each of theplurality of leads, and the second resin is arranged to stretch over thefirst resin that extends from inside the first cutout part toward thepart of the side surface of the semiconductor element mounting part, todirectly cover the part of the side surface of the semiconductor elementmounting part, and is also arranged to stretch over the first resin thatextends from inside the second cutout part toward the part of the sidesurfaces of each of the plurality of leads, to directly cover the partof the side surfaces of each of the plurality of leads.
 4. The substratefor semiconductor elements as claimed in claim 3, further comprising:another resin part provided on a surface of the resin part so as to fillregions where the semiconductor element mounting part and the pluralityof leads are not provided, wherein the third surface of thesemiconductor element mounting part and the first surface of each of theplurality of leads project from the surface of the resin part, whereinthe other resin part has a multi-layer structure including a third resinand a fourth resin, wherein the third resin is arranged to make contactwith side surfaces of the semiconductor element mounting part exposedfrom the resin part, the side surfaces of each of the plurality of leadsexposed from the resin part, an end surface of each of the plurality ofleads opposing the semiconductor element mounting part and exposed fromthe resin part, and a surface of the first resin, wherein the fourthresin is arranged to sandwich the third resin between the fourth resinand each of the side surfaces of the semiconductor element mounting partexposed from the resin part, the side surfaces of each of the pluralityof leads exposed from the resin part, the end surface of each of theplurality of leads opposing the semiconductor element mounting part andexposed from the resin part, and the surface of the first resin, whereinthe third resin and the fourth resin include a filler, and wherein anamount of the filler included in the third resin is smaller than anamount of the filler included in the fourth resin.
 5. The substrate forsemiconductor elements as claimed in claim 2, wherein the resin partexposes the fourth surface of the semiconductor element mounting partand the second surface of each of the plurality of leads.
 6. Thesubstrate for semiconductor elements as claimed in claim 2, wherein thesecond resin is formed on one of a metal film and a support film, andthe first resin is formed on the second resin, the first resin extendsfrom inside the first cutout part to the fourth surface of thesemiconductor element mounting part, to directly cover the fourthsurface of the semiconductor element mounting part, and also extendsfrom inside the second cutout part to the second surface of each of theplurality of leads, to directly cover the second surface of each of theplurality of leads, and the second resin extends on the first resin thatextends from inside the first cutout part to the fourth surface of thesemiconductor element mounting part to directly cover the fourth surfaceof the semiconductor element mounting part, and also extends on thefirst resin that extends from inside the second cutout part to thesecond surface of each of the plurality of leads to directly cover thesecond surface of each of the plurality of leads.
 7. The substrate forsemiconductor elements as claimed in claim 2, wherein the plurality ofleads are provided at a plurality of locations with respect to thesemiconductor element mounting part.
 8. The substrate for semiconductorelements as claimed in claim 7, wherein the semiconductor elementmounting part is provided in a plurality of regions on the substrate forsemiconductor elements.
 9. The substrate for semiconductor elements asclaimed in claim 8, wherein the semiconductor element mounting part isprovided in each of the plurality of regions that are arranged in amatrix arrangement on the substrate for semiconductor elements, and theplurality of regions of the substrate for semiconductor elements arecuttable into individual pieces that form a plurality of unit substratesrespectively including the semiconductor element.
 10. A semiconductordevice comprising: a substrate for semiconductor elements that includesa plurality of leads respectively including a first surface, a secondsurface opposite to the first surface, side surfaces joining the firstsurface and the second surface, a first end, and a second end oppositeto the first end, a cutout part provided in the second surface at thefirst end of each of the plurality of leads, an external connection partprovided on the second surface at the second end of each of theplurality of leads, wherein each of the plurality of leads has a firstthickness at the cutout part thinner than a second thickness at theexternal connection part, and a resin part covering the side surfaces ofeach of the plurality of leads and exposing the external connection partand the first surface of each of the plurality of leads, wherein theresin part has a multi-layer structure, including a first resin and asecond resin, and having the first resin laminated on the second resin,wherein the first resin is provided in contact with the side surfaces ofeach of the plurality of leads and an inner wall surface of the cutoutpart, the first resin and the second resin include a filler, and anamount of the filler included in the first resin is smaller than anamount of the filler included in the second resin; and a semiconductorelement mounted on the substrate for semiconductor elements, wherein thesemiconductor element and the plurality of leads are electricallyconnected.
 11. The semiconductor device as claimed in claim 10, whereinthe substrate for semiconductor elements further includes asemiconductor element mounting part including a third surface on whichthe semiconductor element is mounted, a fourth surface opposite to thethird surface, and a first cutout part provided in the fourth surface atan outer peripheral part of the semiconductor element mounting part,wherein each of the plurality of leads is arranged at a positionseparated from the semiconductor element mounting part, and includes asecond cutout part provided in the second surface at the first end ofeach of the plurality of leads facing the outer peripheral part of thesemiconductor element mounting part, wherein the resin part holds thesemiconductor element mounting part and the plurality of leads in astate in which the third surface of the semiconductor element mountingpart and the first surface of each of the plurality of leads areexposed, and fills the first cutout part and the second cutout part, andwherein the first resin is arranged to make contact with inner wallsurfaces of the first cutout part and inner wall surfaces of the secondcutout part.
 12. The semiconductor device as claimed in claim 11,wherein the first resin extends from inside the first cutout part towarda part of a side surface of the semiconductor element mounting part, todirectly cover the part of the side surface of the semiconductor elementmounting part, and also extends from inside the second cutout parttoward a part of the side surfaces of each of the plurality of leads, todirectly cover the part of the side surfaces of each of the plurality ofleads, and the second resin is arranged to stretch over the first resinthat extends from inside the first cutout part toward the part of theside surface of the semiconductor element mounting part, to directlycover the part of the side surface of the semiconductor element mountingpart, and is also arranged to stretch over the first resin that extendsfrom inside the second cutout part toward the part of the side surfacesof each of the plurality of leads, to directly cover the part of theside surfaces of each of the plurality of leads.
 13. The semiconductordevice as claimed in claim 12, wherein the substrate for semiconductorelements further includes another resin part provided on a surface ofthe resin part so as to fill regions where the semiconductor elementmounting part and the plurality of leads are not provided, wherein thethird surface of the semiconductor element mounting part and the firstsurface of each of the plurality of leads project from the surface ofthe resin part, wherein the other resin part has a multi-layer structureincluding a third resin and a fourth resin, wherein the third resin isarranged to make contact with side surfaces of the semiconductor elementmounting part exposed from the resin part, the side surfaces of each ofthe plurality of leads exposed from the resin part, an end surface ofeach of the plurality of leads opposing the semiconductor elementmounting part and exposed from the resin part, and a surface of thefirst resin, wherein the fourth resin is arranged to sandwich the thirdresin between the fourth resin and each of the side surfaces of thesemiconductor element mounting part exposed from the resin part, theside surfaces of each of the plurality of leads exposed from the resinpart, the end surface of each of the plurality of leads opposing thesemiconductor element mounting part and exposed from the resin part, andthe surface of the first resin, wherein the third resin and the fourthresin include a filler, and wherein an amount of the filler included inthe third resin is smaller than an amount of the filler included in thefourth resin.
 14. The semiconductor device as claimed in claim 11,wherein the resin part exposes the fourth surface of the semiconductorelement mounting part and the second surface of each of the plurality ofleads.
 15. The semiconductor device as claimed in claim 11, wherein thesecond resin is formed on one of a metal film and a support film, andthe first resin is formed on the second resin, the first resin extendsfrom inside the first cutout part to the fourth surface of thesemiconductor element mounting part, to directly cover the fourthsurface of the semiconductor element mounting part, and also extendsfrom inside the second cutout part to the second surface of each of theplurality of leads, to directly cover the second surface of each of theplurality of leads, and the second resin extends on the first resin thatextends from inside the first cutout part to the fourth surface of thesemiconductor element mounting part to directly cover the fourth surfaceof the semiconductor element mounting part, and also extends on thefirst resin that extends from inside the second cutout part to thesecond surface of each of the plurality of leads to directly cover thesecond surface of each of the plurality of leads.
 16. The semiconductordevice as claimed in claim 11, wherein the semiconductor elementmounting part is provided in each of a plurality of regions that arearranged in a matrix arrangement on the substrate for semiconductorelements, and the plurality of regions of the substrate forsemiconductor elements are cuttable into individual pieces that form aplurality of unit substrates respectively including the semiconductorelement.
 17. The semiconductor device as claimed in claim 10, furthercomprising: a plurality of metal wires configured to electricallyconnect the semiconductor element and the plurality of leads.
 18. Thesemiconductor device as claimed in claim 10, further comprising: aplurality of solder bumps configured to electrically connect thesemiconductor element and the plurality of leads.
 19. The semiconductordevice as claimed in claim 10, further comprising: an encapsulatingresin provided on a surface of the substrate for semiconductor elements,wherein the encapsulating resin encapsulates the semiconductor element.20. The semiconductor device as claimed in claim 17, further comprising:an encapsulating resin provided on a surface of the substrate forsemiconductor elements, wherein the encapsulating resin encapsulateseach of the semiconductor element and the plurality of metal wires.